JPS63183838A - Colored polyurethane elastomer coated corrosion-protective steel material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to various steel sheet piles, steel pipe sheet piles, steel pipe piles, etc., which are widely used for port and river construction, as well as mountain protection and flood control construction.
This invention relates to a heavy corrosion-resistant steel material coated with a colored polyurethane elastomer, which is used for H-beam steel, has a wide coloring range, and has excellent weather resistance.

<Conventional technology and its problems> Most of the conventional heavy corrosion-resistant steel materials such as steel sheet piles, steel pipe sheet piles, and H-beams are black, which is incongruous with the surrounding environment of the structure, and coloring is also a problem from a safety perspective. It is becoming demanded.

Coloring of other structures, especially development of environmentally harmonious colors, is required. Examples of this include power transmission towers, lighting poles, and lighting towers, where galvanized coatings are increasingly being painted.

As shown in Figures 2a and 2b, conventional colored heavily corrosion-resistant steel materials include those that use a polyurethane elastomer layer 3 or a plastic layer 4 as a colored layer, but both of these have drawbacks in weather resistance. be.

Additionally, there is a technique disclosed in JP-A-60-92521, in which colored polyolefin sheets are bonded together using an adhesive, which is similar to the technique used to bond polyethylene sheets (black). . However, it is difficult to adhere colored heavy corrosion-resistant steel materials using this method to complex shapes. Furthermore, since black additives such as carbon black are used, the range of coloring is limited.
Furthermore, reducing the addition of carbon black poses problems such as the possibility that weather resistance performance may deteriorate.

<Objective of the Invention> The object of the present invention is to solve the above-mentioned problems, have a wide range of coloring, have particularly excellent weather resistance (fading resistance), and achieve long-term environmental harmony through the synergistic effect with the long-term durability of polyurethane elastomer. The objective is to obtain a colored heavy corrosion-resistant steel material that maintains its properties and safety.

<Structure of the invention> Such objects are achieved by the present invention as described below.

That is, the present invention provides a polyurethane elastomer coating layer and an acrylic urethane resin coating layer containing a colored pigment on the surface of the steel material via a chemical conversion treatment layer and/or an adhesive layer. The present invention provides a heavy corrosion-resistant steel material coated with a colored polyurethane elastomer.

In addition, the polyurethane elastomer coating layer has a weight ratio of (a) aromatic polyisocyanate and aliphatic and/or alicyclic polyisocyanate (95 to 5).
: Contains polyisocyanate mixed in a ratio of (5 to 95), b, polyol, C1 coloring pigment, and d9 metal-based fatty acid salt of group Ⅰ of the periodic table, and is of the same type as the acrylic urethane resin coating layer. It is preferable to use a heavy corrosion-resistant steel material coated with a colored polyurethane elastomer, which is a colored polyurethane elastomer layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the colored polyurethane elastomer-coated heavy duty corrosion-resistant steel material of the present invention will be described in detail as shown in the accompanying drawings.

As shown in FIG. 1, the present invention provides a special base treatment layer 2 (hereinafter referred to as the first layer) on the surface of a steel material 1, a colored polyurethane elastomer layer 3 (hereinafter referred to as the second layer) preferably based on a mixed polyisocyanate. It is a heavy corrosion-resistant steel material provided with an acrylic urethane layer 5 (hereinafter referred to as the third layer) preferably having the same color as the colored polyurethane layer.

The reason for this three-layer type is that the first layer has adhesive properties,
Particular emphasis is placed on water resistance, cathode peeling resistance, impact resistance and insulation resistance in the second layer, and weather resistance in the third layer, each of which has been given excellent performance.

In addition, when the second and third layers are colored in similar colors, even if scratches are added during transportation or during construction of steel sheet piles, steel pipe sheet piles, etc., the scratches will not be noticeable. There is.

Here, as the preferred coating thickness for each of the three layers, the first layer is 2
0 to 100-1, the second layer has a value of 1 to 5flIff+, and the third layer has a value of 10 to 300-.

Next, each layer will be explained in detail.

Steel materials lined in the present invention include structural steel,
Examples include steel pipe piles, steel pipe sheet piles, steel sheet piles, H-shaped steel, etc. made of high tensile strength steel, resistant steel, sulfuric acid resistant steel, etc.

After the anticorrosion surface of the steel material is descaled and cleaned by blasting such as shot blasting, grid blasting, or sandblasting, or by pickling with sulfuric acid, hydrochloric acid, etc., the first layer is applied.

The first layer is a chemical conversion treatment layer and/or an adhesive layer.

In the present invention, in order to improve the adhesion between the second layer and the surface of the steel material, it is preferable to use a chemical conversion treatment layer, a single layer of an organic resin primer as an adhesive, or a multilayer first layer using a combination of these.

As the chemical conversion treatment, phosphate treatment, chromate treatment, and combination treatment thereof are preferable.

Examples of the phosphate treatment include iron phosphate, zinc phosphate, zinc calcium phosphate, and the like.

The coating amount is 0.2 to 1.0 g/a+2 of iron phosphate.
, zinc phosphate, zinc calcium phosphate is 1.0-3
．． A range of 0 g/112 is preferred. If the amount exceeds these amounts, the film will be brittle and the adhesion and impact resistance of the coating will decrease. Moreover, when the amount is less than these amounts, water resistance decreases.

As the chromate treatment, reactive chromate, electrolytic chromate, and coating-type chromate can be applied, but coating-type chromate is superior in terms of workability. As for the amount of coating, the total amount of chromium is 20 mg/tn” ~ 500 I
IIg/rn”.The amount of chromium is 20mg/rn.
If it is less than 500mg/r, there is no effect on water resistance.
If n' is exceeded, the impact resistance of the coating decreases.

In the case of coating type chromate, apply the treatment liquid to the steel material,
Spray paint or splash paint and let dry. The preferred method for drying the chromate-coated steel is thermal drying using an electric furnace, high-frequency induction heating, or the like. Heating temperature is 60-300
℃ range, preferably 80 to 120℃. In addition,
The coating type chromate treatment liquid has r3"/Cr'+ of 115
A range of ~2/3 is good, with silkasol as a binder,
Additives such as inorganic polymers such as alumina sol and alkyl silicate, or water-soluble polymers such as polyvinyl alcohol, polyacrylic acid, and polyacrylic esters may be added to the chromic acid aqueous solution.

In the present invention, although phosphate treatment and chromic acid treatment alone provide excellent water resistance, a combined treatment of phosphate treatment followed by chromic acid treatment may be performed.

Further, it is preferable to use an organic resin primer as the above-mentioned adhesive, and the organic resin primer has excellent adhesion to a colored polyurethane elastomer coating layer made of epoxy resin, phenol resin, phenoxy resin, or urethane resin alone or in combination. Only the best ones are used.

When applying these organic resin brimers to steel materials,
Apply organic resin primer to steel material to about 10 to 4, preferably 20 to 50, using a roll coater, bar coater,
The adhesive is applied to a uniform thickness using airless spraying, brushing, or ironing, and then heated to harden the adhesive.

In the present invention, a polyurethane elastomer coating layer, which is a second layer, is provided as a corrosion protection layer on the surface of the steel material via the first layer.

The polyurethane elastomer may be any polyurethane obtained from an isocyanate compound and a polyol.

Preferably, the aromatic polyisocyanate and the aliphatic or alicyclic polyisocyanate described below are mixed in a weight ratio (
95-5): A mixed polyisocyanate containing a ratio of (5-95) and having excellent weather resistance is used. Further, in this mixed polyisocyanate, it is preferable to use a metal fatty acid salt of group Ⅰ of the periodic table as described below as a catalyst. By having such a composition, it is possible to obtain a polyurethane elastomer coating layer that has mechanical strength and further has excellent weather resistance and corrosion resistance.

Aromatic and aliphatic and/or f1 cyclic polyisocyanates as curing agents used in mixed polyisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolylene diisocyanate in 1 mol of trimethylpropane. Aromatic polyisocyanates such as 3-mole isocyanate adducts, ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate.

These are aliphatic polyisocyanates such as heptamethylene diisocyanate and an adduct of 3 moles of hexamethylene diisocyanate to 1 mole of trimethylpropane, and representative monoalicyclic polyisocyanates include cyclohexane-1,4 diisocyanate. can.

The mixing ratio of aromatic polyisocyanate and aliphatic and/or alicyclic polyisocyanate is 95 to 5:
It is 5-95. If the aliphatic or alicyclic polyisocyanate content is less than 5%, the resulting polyurethane elastomer will have poor stability against light, and if it exceeds 95%, the physical properties of the polyurethane elastomer will be poor.

Examples of the polyol as a main ingredient include polyether polyols, polyester polyols, and polycaprolactones having an average molecular weight of 100 to 10,000, which are used as raw materials for polyurethane elastomers. If the average molecular weight of the polyol is less than 100 or more than 10,000, the physical properties of the polyurethane elastomer will be poor.

In addition, the metal fatty acid salts of group Ⅰ of the periodic table used as catalysts include formic acid, acetic acid, enanthic acid, capric acid, lauric acid, palmitic acid, stearic acid, These include oleic acid, oxalic acid, succinic acid, and tartrate.

The amount of metal fatty acid salt of Group Ⅰ of the periodic table used is 0.001 to 10 wt% based on the polyurethane elastomer.
Preferably it is 0.002 to 2 wL%.

The reason for using a metal-based fatty acid salt from group Ⅰ of the periodic table as a catalyst is to increase the stability of polyurethane elastomer against light, and although the principle is not clear, it is It is thought that the presence of the fatty acid salt stabilizes the urethane bond.

The manufacturing method for polyurethane elastomer is a two-component reaction between a mixed polyisocyanate as a curing agent and a polyol as a main ingredient, and the mixed polyisocyanate is reacted in excess with the polyol to obtain a urethane prepolymer having NGO groups at the end. , a method of obtaining a polyurethane elastomer by further reacting with a polyol, or a method of obtaining a polyurethane elastomer from a mixed polyisocyanate as a curing agent and a polyol as a main ingredient at once. In this case, the metal fatty acid salt of Group Ⅰ of the periodic table may be added to the curing agent or the main agent, or may be added at the time of mixing the main agent and the curing agent.

The reaction temperature between mixed polyisocyanate and polyol is
By using metal-based fatty acid salts from group Ⅰ of the periodic table,
The temperature is lower than in the case of no catalyst, and is 20 to 200°C, preferably 20 to 120°C.

In the present invention, it is preferable that the polyurethane elastomer layer, which is the second layer, contains a predetermined coloring pigment as described below.

In particular, it is preferable to select and use a coloring pigment that has approximately the same color as the third acrylic urethane resin layer to be described later. The reason is that if the second and third layers are of similar color, even if the steel material gets scratched during transportation or pouring work,
This is because there is an advantage that the scratches are not noticeable.

The coloring pigment added to the polyurethane elastomer composition may be a coloring pigment containing any of known heat-resistant inorganic or organic pigment components.

Pigment components include, for example, titanium white (rutile titanium, anatase titanium, etc.) for white pigments, zinc white, lithopone, lead white, and chromium oxide for green pigments.
Chrome green (a mixture of yellow lead and navy blue (potassium ferrocyanide)), zinc green (a mixture of zinc yellow and navy blue), chlorinated copper phthalocyanine green, phthalocyanine green, naphthol green, dibenzanthurone, malachite green lake, etc. It will be done.

Also, for blue pigments, ultramarine (natural products, synthetic products), navy blue
f, Copper Phthalocyanine Blue, Cobalt Blue, Phthalocyanine Blue, Fost Sky Blue, Indan Stremburu-1 As red pigments, Red Pigment, Red Red, Basic Zinc Chromate, Chrome Permillion Vermilion, Cadmium Red, Para Red, Brilliant Carmine (Condensed Azo Red), Brilliant Scarlet, Quinacridone Red, Lysole Red, Vermilion, Thioindigo Red, Mingamya Red, For yellow pigments: Yellow lead, Zinc Yellow, Yellow Iron Oxide, Titanium Yellow, Fast Yellow, Banza Yellow , Auramine Lake, Penjijin Ero, Indanthrene Ero, etc.

As for the pigment used in the polyurethane elastomer composition of the present invention, it is appropriate that the above-mentioned pigment component is contained in the polyurethane elastomer resin in an amount of 1 to 50% by weight. If the addition ratio of coloring pigments is too small, the color will not be vivid, and if the addition ratio is too high, the strength of the coating layer will deteriorate.
This is not preferred because weather resistance decreases.

Further, fillers, fluorescent brighteners, ultraviolet absorbers, antioxidants, and the like may be added to the colored polyurethane elastomer layer of the present invention, if necessary.

The method for applying a polyurethane elastomer layer to a steel material via an adhesive is as follows: (1) Accurately weigh the polyol, mixed polyisocyanate, metal fatty acid salt, and other ingredients into a suitable container;
There are two methods: (1) mixing thoroughly with a drill mixer, etc. and applying with a trowel, and (2) spray painting using a two-component spray paint machine.

The second layer of the present invention is preferably applied relatively thickly, for example to a thickness of 11 m or more, and if the desired thickness cannot be achieved with two coats, multiple coats may be applied.

In the present invention, in order to improve the weather resistance performance (deterioration of the polyurethane elastomer caused by ultraviolet rays) which is insufficient in the second polyurethane elastomer coating layer, the third layer is further coated with an acrylic urethane layer which is a colored layer.

The acrylic urethane resin used for the third layer is a type that hardens through the reaction of acrylic polyol and isocyanate, and can be colored in almost any color tone from light to dark using the coloring pigments and other materials shown in the colored polyurethane elastomer layer mentioned above. It is.

Further, in the present invention, for the reasons mentioned above, it is preferable to use an acrylic urethane resin blended in a color similar to that of the colored polyurethane elastomer of the second layer as the acrylic urethane resin of the third layer.

Effect〉 Next, the operation of the present invention will be explained.

The colored polyurethane elastomer-coated heavy duty corrosion-resistant steel material of the present invention is composed of layers as shown in FIG. 1, for example.

That is, after cleaning one side of the steel material by ordinary cleaning means such as shot blasting and pickling, a base treatment layer 2 is applied, and a polyurethane elastomer layer 3 is applied with a coating of 1 to 50111.
Apply a thick coating, and then apply a colored acrylic urethane layer 5 of 10-~
300 - Thick coating. Base treatment layer 2 (first
layer) and a polyurethane elastomer layer 3 which is an anti-corrosion layer.
(second layer) plays the role of improving adhesion, impact resistance, water resistance, cathode peeling resistance, and insulation resistance, and furthermore, the colored acrylic urethane layer 5 (third layer) is particularly weather resistant. Excellent in

Since both the colored layer (third layer) and anticorrosive layer (second layer) are formed by applying liquid paint, even complex shapes can be easily coated.

Furthermore, acrylic urethane resin paints can be adjusted to almost any color tone.

Next, an anticorrosive layer (second layer) which is the polyurethane elastomer layer 3 and a colored layer (third layer) which is the acrylic urethane layer 5.
Regarding the adhesion of the anti-corrosion layer, if the surface temperature of the anti-corrosion layer is around room temperature and the acrylic urethane resin is applied, within one week,
The adhesive strength measurement value explained in the example is 100 Kg/c+
Although it may be less than s2, the surface temperature of the anticorrosion layer should be 30℃~
By heating to 60℃ or using preheating when applying the anticorrosive layer, the hardening of the colored layer (third layer) is accelerated, and if left for about 2 to 3 days, an adhesive strength of 100 kg/c12 or more can be obtained. be able to.

Even after 6000 hours of accelerated weathering test (sunshine weather meter), the value did not fall below this value.

Additionally, small scratches may be added to the third layer during transportation and handling before driving, but if the second and third layers are of similar color (same tone), the scratches will be hardly noticeable. .

The third layer has good on-site repairability, and can be handled in the same way as a typical two-component paint, and can be easily applied with a brush or spray.

<Example> EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Heavy-duty anti-corrosion steel materials are exposed to severe corrosive environments over many years and must withstand the impact of driftwood, rocks, sand, mud, etc. Therefore, we have established the test methods and target characteristic values shown below, and conducted each test accordingly. was carried out.

1. Adhesive strength (vertical tensile test, room temperature) (0.5 cm/
min) ---------40 gf/c ■2 or more 2, impact strength (pen 5/8'', load 5 g, room temperature) (Gardner impact!I) --------- ---3, OKgf, m or more 3, hot water resistance (60℃, tap water, 30 days) (no edge seal) ......No peeling from the edge 4, wet salt water resistance (60 ℃, 3!4 NaCIL, 30 days)
(No end seal) -------3, gf to 0, m or more 5, salt spray resistance (35℃, 5$NaCj!, 30 days) (cross cut)... ...No peeling from the cross-cut part 6, Cathode peeling resistance (room temperature, 3% KCj 2.30 days) (3.3V, 5mm + diameter) ...-1. No peeling from the initial hole 7, Insulation Resistance (so℃, 3N NaCIL, 30 days) (5
0V, after 1 minute) ・・・・・・10aΩ・l112 or more 8. Concealability (concealability is measured according to JIS 85400) 9. Weather resistance (accelerated weather resistance tester) (Sunshine Weather Meter 6000 hours) ) ・・・・・・・・・Slight discoloration and chalking.

(Example 1 and Comparative Example 1) A black polyurethane elastomer (diphenylmethane 4,4'-diisocyanate 30 parts by weight, 100 parts by weight of polyester polyol, 3 parts by weight of graphite), and further 8 to 300 #m
Thick acrylic urethane resin paint (acrylic polyol 8
0 parts by weight and 20 parts by weight of aliphatic isocyanate). The six colors of the acrylic urethane resin were used: blue, green, yellow, gray thread, sky blue, and brown.

Conventional black polyurethane elastomer (
Diphenylmethane-4,4″-diisocyanate 100
parts by weight, 30 parts by weight of polyester polyol, and 3 parts by weight of graphite) were also tested at the same time. In addition, the steel material used was a steel sheet pile with a thickness of 13 mm, and after chromate treatment as a base treatment, epoxy resin was applied to 50-.

Tables 1 and 2 summarize the various test results.

(1) Adhesive strength A tensile test was conducted at a speed of 0.5 cm/min using a tensile tester.

Both the coloring material of the present invention and the conventional material as a comparative material
It showed an adhesive strength of Kg7cm2 or more.

All colorants broke at the interface between polyurethane elastomer and acrylic urethane.

The conventional material broke within the polyurethane elastomer coating.

(2) Impact strength Gardner set impact tester (pencil 5/8", impact body 5
) was used to determine the impact strength.

Cracks and peeling of the coating were checked using a pinhole detector. Approximately 2.5 for both coloring materials and conventional materials
Good results were shown with a coating thickness of 3.5 g-m or more.

(3) Water Resistance' In the hot water resistance test, wet salt water resistance test, and salt water spray resistance test, almost no peeling from the end face or scratch area was observed for both the colored material and the conventional material, indicating excellent water resistance.

(4) Resistance to cathodic peeling The test material from which the coating material of diameter 5 ■ was removed was immersed in a 3% KCf solution, a voltage of 3.3 V was applied, and the coating was left for 30 days, allowing the coating to peel off from the initial pores. I asked for the distance.

No peeling of the coating from the initial pores was observed for both the colored material and the conventional material, indicating good results.

(5) Insulation resistance 3% Na (, It was immersed in a warm solution of 60° C. for 30 days, a voltage of SOV was applied between the electrodes, and the insulation resistance was measured after 1 minute.

Both colored materials and conventional materials are 8.5×109Ω・m
It showed a high resistance value of 2 or more.

(6) Concealability Concealability is determined by measuring the concealment rate according to JIS 5400 mentioned above, and from the correspondence with visual observation, when the concealment rate is 98% or higher, the underlying color cannot be seen at all, and the concealment is good, and the concealment rate is 90%.
As described above, when the hiding rate is less than 98%, the color of the underlying layer can be seen if you pay attention, and the hiding property is considered to be good, and when the hiding rate is less than 90%, the color of the underlying layer is seen through and the hiding property is judged to be poor.

When white acrylic urethane resin is coated on black polyurethane elastomer (10 units thick), the hiding rate is 95.
%, but with the same thickness of green-colored acrylic urethane resin, the hiding rate was 98%, and the hiding property was almost good.

Further, in the case of a sky blue acrylic urethane resin having a thickness of 8 Jjm, the hiding rate was about 90%, and the coloring was insufficiently clear.

Therefore, it has been found that it is preferable to form the colored acrylic urethane resin layer to a thickness of 10 mm or more.

(7) Regarding the test material coated with weather-resistant colored acrylic urethane resin at a thickness of 100-600 mm using a sunshine weather meter,
An accelerated weathering test was conducted for up to 0 hours, and changes in color tone of the coloring material and conventional material were investigated.

For color tone measurement, 5M-3 manufactured by Suga Test Instruments Co., Ltd. was used.

Evaluation of color tone measurement values and color tone change ΔE are shown in Table 2 (Note 1.
As shown in 2).

As can be seen at a glance from the color change ΔE in Table 2, the material of the present invention in which the acrylic urethane resin was coated on the polyurethane elastomer showed very excellent weather resistance with little color change in all colors. On the other hand, with conventional materials, the coating deteriorated significantly and the black polyurethane elastomer caused chalking when visually observed. Accelerated Slave Resistance Test 2000
There was a tendency for the color tone to change significantly within a short period of time, and then to change somewhat gradually.

Visually, the change in color of the acrylic urethane resin was comparable to water stains in the cooling water during the test. A slight difference in weather resistance due to color tone was observed between acrylic urethane resins. Light color tones such as sky blue and light blue threads had little change in color tone, while slightly darker color tones such as blue, green, and brown had a slightly larger change.

Table 2 (Part 1) Table 2 (Part 2) Note 1) Evaluation of color tone measurement values Bright +←L→-Dark reddish +←a→-Greenish yellow Taste +←b→-i't Taste Note 2) Color tone change △ E = (Lo-L)'+ (ao-a)
2+ (bo-b) 2LO+ ao, b6: Color measurement value before test, a, b: Color measurement value after test (Example 2 and Comparative Example 2) 2, which is the standard film thickness of heavy anti-corrosion coated steel material. Aiming at 5+a+a (the measured film thickness is shown in Table 1), a colored polyurethane elastomer (30 parts by weight of diphenylmethane-4°4'-diisocyanate, 100 parts by weight of polyester polyol) was used.
Parts by weight, 3 to 15 parts by weight of color pigment, 1 part by weight of calcium tartrate
Then, an acrylic urethane resin (80 parts by weight of acrylic polyol, 20 parts by weight of aliphatic isocyanate) of the same color was further applied in a thickness of about 100 mm. Colored polyurethane elastomer and acrylic urethane resin have five color tones: blue, green, yellow, red, and brown.
Colored polyurethane elastomers were used with different composition ratios of mixed polyisocyanates.

The manufacturing method is 5m long steel sheet pile (4001fx130
Hx 13. After blasting Oma+t) and applying a coating type chromate treatment agent (chromic acid compound),
The steel was heated to 100°C and airless spray coated with an amine-curing epoxy primer to a thickness of about 30 units. When the steel temperature reached 60°C, a colored polyurethane elastomer was applied to a target of 2.5m+a. After 30 to 60 minutes, an acrylic urethane resin colored in the same color was applied once to three times to a thickness of 8 to 300 #m.

Table 3 summarizes the various test results.

(1) Adhesive strength (vertical adhesive strength) A tensile test was conducted using a tensile tester at a speed of 0.5 cm/min.

A colored polyurethane elastomer obtained within the scope of the present invention from a mixed polyisocyanate-1, a polyol colored pigment, and a metal fatty acid salt of No. 1 of the periodic table is 100 gf.
The adhesion strength was greater than /cm''.

The same was true when the amount of aromatic polyisocyanate was large.

In this case, the fracture position was between the polyurethane elastomer and the acrylic urethane resin.

(2) Impact strength Gardna complete impact tester (N core 578″, impact body 5
) was used to determine the impact strength.

Cracks and peeling of the coating were checked using a pinhole detector.

When the amount of aliphatic or polycyclic polyisocyanate was too large, the impact strength was poor.

(3) Hot water resistance After being immersed in a 3% NaCl solution at 60° C. for 30 days, the peeling width of the coating from the end face and the vertical tensile strength of the bonded portion were determined.

Similar to the adhesion strength and impact strength, when the aliphatic content was too large, peeling from the end face was observed.

(4) Cathode peeling resistance The test material from which the coating material with a diameter of 5 ms + was removed was reduced to 3% ci.
A hot solution was applied, a voltage of 3.3 V was applied, and the coating was left to stand for 30 days, and the peeling distance of the coating from the initial hole was determined. Similar to the adhesion strength and Ii force strength, when the aliphatic content was too large, peeling from the initial pores was observed.

(5) Concealability Concealability is measured by measuring the concealment rate according to 5400 on the above-mentioned month S, and from the correspondence with visual observation, when the concealment rate is 98% or more, the concealment is good, and when the concealment is 90% or more and less than 98%, the concealment is poor. It was determined that the coverage was good, and that the coverage was poor if the coverage was less than 90%.

Since the colored polyurethane elastomer layer (second layer) and the acrylic urethane resin layer (third layer) have similar colors, it is difficult to confirm the hiding property, so the second layer was made of black polyurethane elastomer and the hiding rate was measured. . When the thickness of the third layer was 10 units thick, the hiding rate was 98%, which was good, but when the thickness was 8 -, the hiding rate was about 90%, and the original color tone of the third layer could not be exhibited. . Moreover, when the thickness of the third layer was 15 or more, the hiding property was perfect.

Therefore, the thickness of the third layer is preferably 10-F or less.

(6) A test was carried out after 6000 hours using a weather resistance accelerated weather resistance tester (Sunshine Weather Meter), and changes in the color tone of the coating (second layer two-colored polyurethane elastomer, third layer nyacryl urethane resin) were evaluated. investigated.

For color tone measurement, 5M-3 manufactured by Suga Test Instruments Co., Ltd. was used, and the evaluation of the color tone measurement values was as follows: Bright +←L→-Dark Reddish+←a→-Yellow Taste +←b→-Blue Taste , and the color tone change is expressed as
)2LO+ ao, bo: Color measurement value before test, a, b
: Measured by color measurement after the test.

When an acrylic urethane resin of a similar color was applied onto the colored polyurethane elastomer layer (inventive examples 1 to 7), there was very little discoloration and excellent weather resistance was observed.

Colored polyurethane elastomer layer only (Comparative Examples 1 to 3)
The color difference ΔE was larger than that of acrylic urethane resin, and it was superior to conventional polyurethane elastomers, but the color fading was somewhat noticeable.

In addition, colored polyurethane elastomers in a range outside the range of the curing agent blending ratio of the present invention suffered from significant discoloration, and all of the coloring was tinged with white.

The above test results are summarized as follows.

Colored polyurethane elastomer (second layer).

Sufficient mechanical properties and water resistance are obtained within the scope of the present invention, and the weather resistance is superior to that of conventional black polyurethane elastomers. By applying a layer Ii, it exhibits extremely excellent weather resistance.

<Effects of the Invention> According to the colored polyurethane elastomer-coated heavy corrosion-resistant steel material of the present invention, a polyurethane elastomer coating layer is formed on the surface of the steel material through a predetermined base layer, and an acrylic urethane resin coating layer is formed on the surface of the steel material. , the surface layer has a wide coloring range, has excellent weather resistance (fading resistance), and has a synergistic effect with the long-term durability of polyurethane elastomer, so it can maintain long-term environmental friendliness and safety.

In particular, if the polyurethane elastomer coating layer and the acrylic urethane resin coating layer are made of similar colors, even if the steel material is scratched during transportation or pouring work,
The scratches are not noticeable, and the on-site repairability of the scratches is also good.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the steel material of the present invention. Figures 2a and 2b are schematic cross-sectional views of conventional steel materials. Explanation of symbols 1 - Steel material, 2 - Base treatment layer, 3 - Polyurethane elastomer layer, 4 - Plastic layer (black or colored), 5 -
acrylic urethane layer

Claims (2)

[Claims] (1) A polyurethane elastomer coating layer is provided on the surface of the steel material via a chemical conversion treatment layer and/or an adhesive layer, and an acrylic urethane resin coating layer containing a colored pigment is provided on the coating layer. Colored polyurethane elastomer coated heavy duty anti-corrosion steel (2) The polyurethane elastomer coating layer has a weight ratio of aromatic polyisocyanate and aliphatic and/or alicyclic polyisocyanate (95 to 5):
a polyisocyanate mixed in a ratio of (5 to 95); b) a polyol; c) a colored pigment; and d) a metal fatty acid salt of Group II of the periodic table; The heavy corrosion-resistant steel material coated with a colored polyurethane elastomer according to claim 1, which is a colored polyurethane elastomer layer colored in a similar color.